The aim of this study was to compare the patient-reported outcome measures Neck Disability Index (NDI) and visual analog scale (VAS) with the Patient Reported Outcomes Measurement Information System (PROMIS) physical function (PF) and pain interference (PI) measures, respectively, and to determine their correlations in a surgical population longitudinally.
Legacy outcome measures such as NDI and VAS are essential for analyzing treatments in spine surgery for cervical disc herniations with radiculopathy. Despite their usefulness, administrative burdens impose limits on completion of these measures. PROMIS was developed as a patient outcome measure in order to improve reporting of patient symptoms and function and to reduce administrative burden. Despite early positive results of PROMIS in orthopedics, NDI and VAS scores have not been compared with PROMIS scores in patients with cervical disc herniations with radiculopathy.
Eighty patients undergoing surgery for cervical disc herniations with radiculopathy were included. All patients were treated at the same tertiary spine center. Patients were seen and PROMIS PF and PI, NDI, and VAS arm and neck pain scores were collected preoperatively and at 1 year postoperatively. Correlations between NDI, VAS, and PROMIS PF and PI were quantified using Pearson correlation coefficients. Two-tailed Student t-tests were used to demonstrate correlation significance, with alpha = 0.05.
All 80 (100%) patients completed all preoperative questionnaires. Fifty-seven (72%) and 75 (94%) patients completed all questionnaires at baseline and at the 6-month and 1-year follow-ups, respectively. PROMIS PF and NDI scores demonstrated a strong negative correlation, with Pearson r values of −0.81, −0.77, and −0.75 at baseline, 6 months, and 1 year. PROMIS PI and VAS neck pain scores demonstrated a moderately positive correlation, with Pearson r values of 0.51, 0.61, and 0.6. PROMIS PI and VAS arm pain scores demonstrated a moderately positive correlation, with Pearson r values of 0.46, 0.47, and 0.45.
PROMIS PF scores have a strong negative correlation with NDI scores at baseline and in the postoperative course in patients undergoing surgery for cervical disc herniations with radiculopathy. PROMIS PI scores have a moderately positive correlation with VAS neck and arm pain scores at baseline and in the postoperative course. Surgeons may factor these correlation results into the interpretation of patient-reported outcome measures in patients with cervical radiculopathy. Use of PROMIS PF and PI for this patient population may reduce administrative burden while providing reliable outcomes data.